Hydraulic control circuit

ABSTRACT

A hydraulic control circuit is disclosed herein that has particular utility with a self-propelled construction equipmenttype of vehicle, such as a crane or an excavator, e.g., a backhoe. The circuit includes a first pump means for providing pressurized fluid for actuating at least one fluid motor in the circuit in one direction, and a second pump means for providing pressurized fluid for actuating at least one fluid motor in the circuit in one direction, and a second pump means for providing pressurized fluid for operating the fluid motor in an opposite direction. A first control valve means is associated with the first pump means and a second control valve means is associated with the second pump means, with each control valve means having a blocked position for preventing flow of fluid therethrough and at least one open position permitting fluid to flow therethrough. The control valve means are alternatively positionable in the blocked position, and the conduit means of the circuit are arranged such that when the first control valve means is in the blocked position and the second control valve means is in the open position, one line to the fluid motor means is pressurized for operating the fluid motor means in one direction, while another line connected to the fluid motor means is a low pressure line open to tank. When the first control means is in the open position and the second control means is in the blocked position, the last-mentioned line is pressurized for moving the fluid motor means in an opposite direction, while the first-mentioned line is a low-pressure line connected to tank.

United States Patent [72] Inventor Allan J. Albrecht Rothschild, Wis. [21] Appl. No. 16,487 [22] Filed Mar. 4, 1970 [45] Patented [73] Assignec July 20, 1971 J. 1. Case Company [54] HYDRAULIC CONTROL CIRCUIT Primary Examiner-Edgar W. Geoghegan Att0rneyDressler, Goldsmith, Clement and Gordon ABSTRACT: A hydraulic control circuit is disclosed herein that has particular utility with a self-propelled construction equipment-type of vehicle, such as a crane or an excavator, e.g., a backhoe. The circuit includes a first pump means for providing pressurized fluid for actuating at least one fluid motor in the circuit in one direction, and a second pump means for providing pressurized fluid for actuating at least one fluid motor in the circuit in one direction, and a second pump means for providing pressurized fluid for operating the fluid motor in an opposite direction. A first control valve means is associated with the first pump means and a second control valve means is associated with the second pump means, with each control valve means having a blocked position for preventing flow of fluid therethrough and at least one open position permitting fluid to flow therethrough. The control valve means are alternatively positionable in the blocked position, and the conduit means of the circuit are arranged such that when the first control valve means is in the blocked position and the second control valve means is in the open position, one line to the fluid motor means is pressurized for operating the fluid motor means in one direction, while another line connected to the fluid motor means is a low pressure line open to tank. When the first control means is in the open position and the second control means is in the blocked position, the last-mentioned line is pressurized for moving the fluid motor means in an opposite direction, while the firstmentioned line is a low-pressure line connected to tank.

PATENTED JUL20 r971 HYDRAULIC CONTROL CTlliClUllT BACKGROUND OF THE INVENTION Construction equipment vehicles, such as cranes or backhoes, have conventionally included a plurality of fluid motors for accomplishing useful work. lllustratively, piston and cylinder type of fluid motors are used in a crane having a telescoping boom structure to extend and retract the boom sections relative to one another. Fluid motor means are also utilized in cranes to actuate the winch and hoist structure associated with the boom structure. It is quite common to provide means for stablilizing construction vehicles, such as cranes or backhoes, as they are performing their intended function, and conventionally the stabilizing means takes the form of support members that are movable from a retracted or stored position during transport of the vehicle, to a ground engaging position while the working means on the vehicle is performing the desired function. Conventionally, a stabilizing means is provided at the front and rear of the vehicle on both sides thereof.

In hydraulic circuits for vehicles of the above-described type, it is conventional to utilize a first pump means for providing fluid under pressure for actuating the fluid motors in one direction, and a second pump means for providing fluid under pressure for operating the fluid motors in an opposite direction. Such circuits have heretofore necessitated the use of a large number of control valves which have rendered such circuits unduly complex, and which have made such circuits initially expensive and subsequently difficult and time consummg to maintain.

SUMMARY OF THE INVENTION The present invention provides a simplified two pump system of the above-described type that utilizes a minimum of control components in a circuit without in any way detracting from the function of the system. To this end, the circuit of the present invention includes first and second pump means connected in a hydraulic circuit with a fluid reservoir, with at least one work accomplishing fluid motor being provided in the circuit. The output of the first pump means is connected with the fluid motor for operating the motor in one direction and the output of the second pump means is connected with the fluid motor for operating the motor in an opposite direction. A first control valve means is connected in the circuit between the first pump means and tank, with the first control valve means having a closed position for blocking fluid flow therethrough and at least one open position allowing fluid to flow therethrough. A second control valve means is connected in the circuit between the second pump means and tank, with the second control valve means having a closed position for blocking fluid flow therethrough and at least one open position allowing fluid to flow therethrough.

In use, either the first control valve means is positioned in the blocked position, while the second control valve means is in the open position, or the first control valve means is positioned in the open position while the second control valve means is in the blocked position. When the first control valve means is in the blocked position, the line from the first pump means to the fluid motor means is pressurized so that the fluid motor means can be operated in one direction. When the first control valve means is in the open position, the line from the second pump means is connected to the fluid motor means so that it can be operated in the opposite direction.

BRIEF DESCRIPTION OFTHE DRAWING The single FIGURE is a diagrammatic view of a preferred embodiment of the circuit of the present invention.

DETAILED DESCRlPTlON While this invention is susceptible of embodiment in many different forms, there is shown in the drawing and will herein be described in detail a preferred embodiment of the invention, with the understanding that the present disclosure is to be considered as an exemplification ofthe principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

The control circuit of the present invention will be described herein in connection with a mobile crane, although it will be readily apparent to those skilled in the art that the circuit of the present invention can be used with similar equip ment utilizing a two pump hydraulic circuit, such as a backhoe. A mobile crane of the type with which the present invention has particular utility is a self-propelled vehicle that is driven by an engine it). The control circuit of the present invention includes a first pump 12 and a second pump M, with both pumps preferably being driven by the engine 10. A first bank 116 of control valves is associated with pump 12 for controlling certain functions of the crane, and a second bank 18 of control valves is associated with pump M for controlling other functions of the crane. Valve bank 16 is connected to pump 12 for receiving fluid under pressure therefrom by lines 20 and 22. Valve bank ltl is connected to pump 14 for receiv ing fluid under pressure therefrom by lines 24 and 26.

In the illustrated embodiment, control bank valve 16 includes three individual valves 2%, 30 and 32, and each of valves 28, 3t) and 32 is a three-position, fourway valve. In a specific embodiment of the invention, valves 23, 30 and 32 are manually actuated, and valve 28 controls the flow of fluid to the lift cylinder (not shown) of the crane through lines 34 and 36, while valve 32 controls the flow of fluid to the main winch (not shown) of the crane through lines 38 and dill. Control valve 30 has an open central position, but the lines 42 and 44 connected to valve 30 are blocked, as indicated at 46 and 4m, so that fluid flow through the bank 16 of control valves 2%, 30 and 32 is prevented until valve 30 is actuated.

Control valve bank l8 includes a plurality of individual control valves 50, 52, 5d and 56. The control valves of bank 18 are all three-position, four-way valves; and in a specific embodiment of the invention, valve 50 may be utilized to control the flow of fluid to a swing motor (not shown) of the crane through lines 58 and 60. In the specific embodiment of the invention, control valve 54 may be utilized to control the flow of fluid to the crown cylinder (not shown) of the crane boom through lines 62 and 64, while control valve 56 may be utilized to control the flow of fluid to the crane winch (not shown) through lines as and 6b. In the preferred embodiment of the invention, valves 50, 52, 54 and 56 are each manually actuated, although it will be apparent to those skilled in the art that other modes of operation can be utilized. Control valve 54 has an open central position, but the fluid lines 70 and 72 leading from the valve are blocked, as is illustrated at 74 and 76 so that when valve 543 is not actuated, flow through valve bank is is prevented. During operation of the circuit, valves 30 and 54 are alternatively actuated, as will hereinafter appear.

As is mentioned above, in self-propelled construction vehicles such as cranes, it is conventional to provide stabilizing means at each corner of the vehicle to provide a firm base from which the useful work can be completed. The stabilizing means are illustrated generally herein at 78, 80, 82 and M, and since the circuitry for each stabilizing means is identical, only the circuit components for stabilizing means 78 will be described in detail.

The control circuit of the present invention has particular utility in connection with a stabilizing means in the form of Outriggers that are articulated to the frame of the vehicle in a manner such that a compound motion is required to shift the stabilizing means from a retracted or stored transport position to an extended vehicle supporting position. Fluid motor means db and W are provided for effecting this compound movement, although it will be appreciated that with different types of stabilizing means only a single fluid motor may be required. As is evident from the drawing, fluid motors 86 and 88 are of the cylinder and piston variety, with a line 90 being connected to the head end of fluid motor 86 and a line 92 being connected to the rod end of fluid motor 86. ln a similar manner, a line 94 is connected to the head end of fluid motor 88, while a line 96 is connected to the rod end of fluid motor 88. The circuit further includes a control valve 98 for controlling the direction of operation of fluid motors 86 and 88 and a line 100 establishes communication between control valve 98 and first pump 12, while a line 102 establishes communication from control valve 98 and second pump 14. Lines 104 and 106 lead from control valve 98 to a sequence valve 108, that prevents the passage of fluid to fluid motors 86 and 88 until a predetermined pressure is reached. Control valve 98 is preferably actuable by a solenoid 110 that is positioned at a location remote from the stabilizing structure.

In use, assuming that it is desired to move the stabilizing means in a first direction, i.e., from a retracted position to a ground engaging position, control valve 54 of bank 18 is actuated to allow fluid to freely flow through the bank 18 and to a fluid reservoir in the form of a tank 112 through line 114, while the control valve 30 blocks fluid flow through valve bank 16. Under the circumstances, the portion of the circuit between pump 12 and valve bank 16 becomes pressurized, with high pressure fluid flowing through lines 22 and 100 to control valve 98. When control valve 98 is actuated, fluid under pressure will flow through lines 106, through sequence valve 108, and through lines 90 and 941 to head ends of fluid motors 86 and 88, respectively. The pistons within the cylinders of the fluid motors will move in a first direction, i.e., downwardly as illustrated in the drawing, and fluid from the rod ends of motors 86 and 88, respectively, will flow through respective lines 92 and 96, through the sequence valve 108. Under these circumstances, the fluid from the rod end of the fluid motors will flow through control valve 98 and through line 102, (which serves as a high pressure line from pump 14 when the fluid motors are actuated in an opposite direction) directly to tank 112.

When it is desired to actuate the fluid motors 86 and 88 in an opposite direction, i.e., to have the pistons move upwardly as illustrated in the drawing, control valve 30 in bank 16 is actuated to allow fluid to freely flow therethrough, while control valve 54 blocks the flow of fluid through bank 18. Under these circumstances, the circuit between second pump 14 and valve bank 18 becomes pressurized, so that high-pressure fluid is present in line 102. The output from pump 12 flows to the valve bank 16 through line 20, and from the valve bank to tank 112 through line 114. When control valve 98 is actuated, fluid under pressure flows through line 104 and through sequence valve 108 to the rod ends of fluid motors 86 and 88, respectively, through lines 92 and 96, respectively. The pistons of fluid motors 86 and 88 move upwardly, and the low pressure fluid from the head ends of the fluid motors 86 and 88 flows through lines 90 and 94, respectively, through sequence valve 108, and to tank, through lines 1%, and line 100. Thus, it will be appreciated that when control valve 54! blocks fluid flow through valve bank 18, line 100 operates as a low-pressure line that is connected directly to tank, while when control valve 30 is blocked, line 100 operates as a highpressure line.

From the foregoing, it will be appreciated that an extremely simplified system control circuit has been provided for a two pump hydraulic system that effectively minimizes the number of components that must be provided in the system while at conduit means in said circuit connecting the output of said first pump means with said fluid motor for operating said motor in one direction; second conduit means in said circuit connecting the output of said second pump means with said fluid motor for operating said motor in an opposite direction; a first control valve means, said first control valve means having a closed position for blocking fluid flow therethrough and at least one open position allowing fluid to flow therethrough; third conduit means connecting said first control valve means in said circuit between said first pump means and said fluid reservoir; second control valve means, said second control valve means having a closed position for blocking fluid flow therethrough and at least one open position allowing fluid to flow therethrough; fourth conduit means in said circuit connecting said second control valve means between said second pump means and said fluid reservoir; and means for alternatively positioning either said first control valve means in said blocked position and said second control valve means in said open position, whereby said first and third conduit means are pressurized by fluid from said pump means and said second and fourth conduit means are open to said fluid reservoir so that said fluid motor means can be operated in said one direction, or said first control means in said open position and said second control valve means in said blocked position, whereby said second and fourth conduit means are pressurized by fluid from said second pump means and said first and third conduit means are open to said fluid reservoir so that said fluid motor means can be operated in said opposite direction.

2. A control system as set forth in claim 1 in which a further control valve means is provided in said circuit, said first and second conduit means being connected to said further control valve means; and wherein said fluid motor means is as cylinder having a piston therein, there being a fifth conduit means connected between the further control valve means and the rod end of the fluid motor and a sixth conduit means connected between the further control valve means and the head end of the fluid motor, said further control valve means, when actuated, allowing high-pressure fluid to flow to the rod end of said fluid motor through said fifth conduit means when said first control valve means is in the closed position, and allowing high-pressure fluid to the head end of the fluid motor through said sixth conduit means when said second control means is in the closed position.

3. A control system as set forth in claim 2 wherein said further control valve means is actuated by a solenoid.

4. A control system as set forth in claim 1 wherein a plurality of fluid motors are connected in parallel in said circuit.

5. A control system as set forth in claim 1 wherein a common return line connects said first and second control valve means to the fluid reservoir.

6. A control system as set forth in claim 1 wherein both said first and second control valve means are defined by a bank of control valves, each bank including a plurality of individual control valves.

7. A control system as set forth in claim 6 wherein one control valve of each bank provides the respective closed and open positions.

8. A control system as set forth in claim 7 wherein said one control valves are manually actuable.

Patent No.

Inventor(s) Column 2, line valve bank Column 2, line Column 3, line Column 3,

Column line Column L, line Column line Column line Signed and (SEAL) Attest:

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Dated July 20, 1971 Allan J. Albrecht It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

"control bank valve" should be control "crown" should be crowd "lines" should be line after "96," insert and lines" should be line delete "system".

after "from said" insert first after "control" insert valve as should be a after "control" insert valve sealed this 15th day of February 1972.

EDWARD MFLETCHER, JR.

Attestinr; Officer FORM PC4-1050 (10-69) ROBERT GOTTSCHALK Commissioner of Patents USCOMM-DC 503754 59 US GOVERNMENT PRINTING OFFICE: I969 0-366-334 In the Abstract, line 7, "actuating" should be operating 

1. A control system comprising: a fluid reservoir; first and second pump means connected in a hydraulic circuit with said fluid reservoir; at least one fluid motor in said circuit; first conduit means in said circuit connecting the output of said first pump means with said fluid motor for operating said motor in one direction; second conduit means in said circuit connecting the output of said second pump means with said fluid motor for operating said motor in an opposite direction; a first control valve means, said first control valve means having a closed position for blocking fluid flow therethrough and at least one open position allowing fluid to flow therethrough; third conduit means connecting said first control valve means in said circuit between said first pump means and said fluid reservoir; second control valve means, said second control valve means having a closed position for blocking fluid flow therethrough and at least one open position allowing fluid to flow therethrough; fourth conduit means in said circuit connecting said second control valve means between said second pump means and said fluid reservoir; and means for alternatively positioning either said first control valve means in said blocked position and said second control valve means in said open position, whereby said first and third conduit means are pressurized by fluid from said pump means and said second and fourth conduit means are open to said fluid reservoir so that said fluid motor means can be operated in said one direction, or said first control means in said open position and said second control valve means in said blocked position, whereby said second and fourth conduit means are pressurized by fluid from said second pump means and said first and third conduit means are open to said fluid reservoir so that said fluid motor means can be operated in said opposite direction.
 2. A control system as set forth in claim 1 in which a further controL valve means is provided in said circuit, said first and second conduit means being connected to said further control valve means; and wherein said fluid motor means is as cylinder having a piston therein, there being a fifth conduit means connected between the further control valve means and the rod end of the fluid motor and a sixth conduit means connected between the further control valve means and the head end of the fluid motor, said further control valve means, when actuated, allowing high-pressure fluid to flow to the rod end of said fluid motor through said fifth conduit means when said first control valve means is in the closed position, and allowing high-pressure fluid to the head end of the fluid motor through said sixth conduit means when said second control means is in the closed position.
 3. A control system as set forth in claim 2 wherein said further control valve means is actuated by a solenoid.
 4. A control system as set forth in claim 1 wherein a plurality of fluid motors are connected in parallel in said circuit.
 5. A control system as set forth in claim 1 wherein a common return line connects said first and second control valve means to the fluid reservoir.
 6. A control system as set forth in claim 1 wherein both said first and second control valve means are defined by a bank of control valves, each bank including a plurality of individual control valves.
 7. A control system as set forth in claim 6 wherein one control valve of each bank provides the respective closed and open positions.
 8. A control system as set forth in claim 7 wherein said one control valves are manually actuable. 